1. Field of the Invention
The present invention relates generally to wafer handling systems, and more particularly to a system that allows wafers to be moved from point to point under known conditions of acceleration and velocity as well as the rate-of-change of derivative of acceleration called jerk.
2. Description of the Prior Art
In the processing of semiconductor wafers, from which semiconductor chips are produced, the wafers must be transferred from one location to another. In the majority of semiconductor processes, the wafers are oriented such that the disk is parallel to the plane of the floor (the planer orientation). Although the wafer can be rotated such that it is non-planer with the floor in order to facilitate certain semiconductor processes, most of the wafer handling from the wafer storage device, through the tool and then back into another wafer storage device is done with the wafer in this planer orientation. This invention concerns semiconductor wafers or similar substrates that are moving in planer space.
Modern semiconductor wafer processing machines move the wafers with wafer handling robots. Wafer handling robots consist of mechanisms optimized for moving wafers. Some semiconductor processes are conducted in a vacuum chamber. As a result, some of the wafer handling robots operate inside the vacuum environment and some wafer handling robots operate outside the vacuum environment. So called atmospheric wafer handling robots handle wafers outside the vacuum chamber and serve to pass wafers to and from the vacuum robot which operates inside the vacuum chamber. All wafer handling robots are equipped with a manipulator which hold the wafer on the end of the robot arm. Sometimes the wafers are grasped by the manipulator. Other times, the wafer simply rests on tiny pads without otherwise being held by the manipulator.